Drinking sugar-sweetened sodas and other beverages may increase the risk of younger women developing colorectal cancer, suggests a new study that was published online in the journal Gut. The study, which includes one author funded by AICR, may help explain the troubling increase in the rise of colorectal cancer among younger men and women in recent years.
Colorectal Cancer on the Rise Among Young Adults
Colorectal cancer is the third most common cancer and cause of cancer-related deaths in the U.S. The vast majority of these cancers are diagnosed among people ages 50 and over. One positive trend is that incidence of U.S. colorectal cancer has been dropping in recent years, with increased screening attributed as a key reason.
Yet, even with this overall decrease, incidence of new cases among adults younger than 50 are on the rise. Since the 1990s, the rate of colorectal cancer has climbed steadily among adults younger than 50 with an increase of over 2 percent annually in recent years. Many of these cases are not diagnosed until the later stages, leading to treatment challenges.
The alarming trend seen among young adults has led to new research working to uncover why it is happening. Cancer diagnosed among adults younger than 50 is called “early-onset colorectal cancer” and it may have distinct risk factors and biology compared to colorectal cancers diagnosed among older adults.
Sweetened Beverages and Colorectal Cancers
In this latest research, scientists analyzed data from approximately 95,000 participants of the Nurses’ Health Study, a large population study that examines the link between risk factors and health among female nurses. The women were between the ages of 25 to 42 when they entered the study in 1989. Every four years, participants answered questions about what beverages they drank and other dietary habits. About 41,000 of the women also recalled their beverage habits during adolescence.
From 1991 until 2015, the researchers identified 109 diagnoses of early-onset colorectal cancer.
Compared with women who drank less than one 8-ounce serving per week of sugar-sweetened beverages, those who drank two or more servings per day had just over twice the risk of developing early-onset colorectal cancer. This link was found after taking into account BMI, smoking, family history and other risk factors. The researchers calculated a 16 percent increase in risk for each 8-ounce serving of sugar-sweetened drink per day. Sugar-sweetened beverages include sodas, along with fruit, sports and energy drinks. A typical can of sugary soda is 12 ounces.
Drinking more sugary beverages from ages 13 to 18 also trended towards increased risk of developing early-onset colorectal cancer as adults, although findings here were not as clear and could be due to chance.
Replacing that sugary drink with milk, coffee and artificially sweetened beverages appeared to lower the risk of early-onset colorectal cancer, the study calculated. Yet, substituting water or tea for the sugary beverage indicated they might lower risk, but the evidence for these beverage replacements was also not clear.
This study shows an association; it does not show that sugary beverages are a direct cause of early-onset colorectal cancer or that coffee and the other beverages are protective.
And because the study only included women, most of whom were white, more work is needed to examine this link in people of more diverse races, ethnicities and genders. The study also could not identify the time window when colorectal cancer developed.
The findings tie together with previous papers by the same research team that point to diet, obesity and the metabolic syndrome as potential culprits in the increasing cases of early-onset colorectal cancer.
One paper published last year found a link between eating high amounts of red meat, refined grains, sweets and other foods common to a Western diet as increasing the risk of an early sign of colorectal cancer called adenomas, compared to those least following the Western diet. This study also pulled data from the Nurses’ Health Study population. The younger women who most followed a prudent dietary pattern – which emphasizes fruits, vegetables, whole grains, nuts and legumes, and can include lean meats and fish – were less likely to develop these early-onset adenomas compared with the women who least followed this pattern.
Other papers show a link between obesity and metabolic syndrome with developing early-onset colorectal cancer. Metabolic syndrome is a group of conditions that includes type 2 diabetes, obesity and high blood sugar. Sugary beverages may play a role in these conditions, the authors note.
Healthy Habits for Lower Risk
AICR’s Cancer Prevention Recommendations include limiting consumption of sugar-sweetened beverages, as regular consumption of these drinks is a cause of weight gain and obesity. Strong evidence has found that having too much body fat is in itself a cause of at least a dozen cancers, including colorectal. (Because the majority of colorectal cancers are among adults over age 50, the overall research was conducted among adults who were diagnosed with the cancer when older.)
Research shows that avoiding processed meat, limiting consumption of red meat, being physically active and eating plenty of whole grains can lower the risk of colorectal cancer. Drinking no alcohol or only moderate amounts, if any, also lowers the risk.
Regular screening remains one of the most important ways to prevent this cancer and it is key to the falling number of U.S. cases. The U.S. Preventive Services Task Force just lowered the recommended age to start screening from 50 to 45. Other groups, such as the American Cancer Society, recommend screenings begin earlier.
Read the findings of AICR’s latest report for more information about lowering risk of colorectal cancer.